The present invention relates to an optical body and a light emitting device.
As a kind of optical body, there is known an optical body in which a light waveguiding phenomenon and a light diffusion phenomenon are combined, for example as disclosed in JP 2012-136199A. Such an optical body is also called a light guide plate. A light extraction unit that diffuses light is formed on a surface of the light guide plate. Light is injected into the inside of the light guide plate from a light source that is provided on a side surface of the light guide plate. The light injected in the inside of the light guide plate, that is, internally propagating light propagates through the inside of the light guide plate while reflecting at surfaces of the light guide plate (that is, interfaces between the inside and the outside of the light guide plate). After that, the internally propagating light is reflected at the light extraction unit, and is emitted from a surface on the opposite side to the surface on which the light extraction unit is formed. That is, the light guide plate emits light injected from a side surface of the light guide plate, from a surface of the light guide plate. Thus, the region where the light extraction unit is formed serves as a light emitting region.
The light guide plate is used as, for example, light emitting bodies for various display devices or light emitting bodies for illumination. Examples of the display device in which a light guide plate is used include various LCDs (for example, an LCD of a local dimming driving system), passive-type display devices, light ornamentation panels for amusement, illumination panels for advertisements such as digital signage, etc. In these display devices, an expression looking as if light stood out from a region where a pattern of the light extraction unit is formed, that is, a light emitting region is enabled by the turning on and off of the light source. Various designs (numerals of speedometers, etc.) are created by the shape of the light emitting region.